This widget might be helpful
Hi, If you want to choose a value from set of predefined vale please use enum as atribute type. Then you can use a drop down while selecting the value. Hope this will help
If you are storing these locations as object then using refrence set selector is best option. Or you can have a yes /no button for every location and onclick you can used a microflow which will attach the respctibe object with location. Then you can retrieve the list of location whenever required using the object through association.